Have an 83 Nighthawk 650 and my electrical system is being a pain with starts. Cleaned the carbs about 4 times after sitting for a couple months determined this was the issue but they are now spotless. Found if I jump the terminals on my solenoid it starts great but with a couple different relays I had it has trouble from the starter button, so it makes me think its not the relay itself. Been looking into the coil relay mod where you use a 30a horn relay and use that to get more power direct to coils.

Has anyone done this on this era? As far as I can see the four wires I have at the solenoid are:

Red: power from ignition switchRed/white: goes to rectifierYellow/red: comes from starter buttonGreen/red: comes from the clutch diode

The mod suggests taking the wire from the kill switch, black/white, but this is nowhere near the solenoid from what I can see. Is this still the route to go? Wanna make sure this works on the DOHC bikes' electrical system before I jump in. Any insight would be great, thanks!

Ok, I read the instructions a few more times and made a drawing of my own. So does this mod take the starter button out of the equation and purely depend on the kill switch? So off=nothing and switch to on and it starts up since there is power to the coils right away? This makes sense somewhat but then the red/white going to the rectifier is left null from what I see, as well as the red from the ignition switch. Is the new relay in addition to the original one since the power still is linked to the bolt on the relay? I may be overthinking this but the write up Im using is in reference to old Suzuki bikes, not Honda so Im flipping between that and my service manual scratching my head an awful lot :/

I did not look at all the details, but the rough drawing in your link does not take either the kill switch or the ignition switch out of the equation. The only difference is they work to operate the relay, which THEN provides power to the coils.

I do a coil relay on nearly all the bikes I rebuild. I follow the diagram shown below:

I run a 12 ga wire directly from the positive terminal of the battery, through a 10 amp inline fuse, to the common terminal (30/51) of the relay. Then continue the 12 ga wire from the Normally Open (87) terminal to the place on the coils where the black and white wire connected. Then connect the black and white wire to the 86 terminal and connect the 85 terminal to ground.

With this done, the black and white wire that WAS supplying pulses to fire the coil is now causing the relay to open and close. When the relay closes, the maximum amount of voltage available is going directly to the coils.

Aha! I read the instructions as replacing the starter solenoid for some reason. Way off...

So last thing I'm a little fuddled on is the black and white wire...this goes from the kill switch back to rhe igniter box and splits into two after the harness for the coils. Do i cut it after the harness before it splits into two to go to the coils? So the signal is coming from the igniter, 86, and 87 goes to the wire that then splits to the coils yes? Thanks much for your help, greatly appreciated

Its' just a little trick to improve your spark by a couple of percentage points. When the power has to travel though the entire wiring harness to get to the coils, you lose as much as a full volt. By going directly from the battery, you get full battery power each time.

Folsoml wrote:Its' just a little trick to improve your spark by a couple of percentage points. When the power has to travel though the entire wiring harness to get to the coils, you lose as much as a full volt. By going directly from the battery, you get full battery power each time.

HA! next thing you'll be using words like "easy" and "simple" and "nothing to it". Electrics to me is like Witchcraft and Sorcery Just give me something to hit with a hammer or turn with a spanner and I'm happy, besides which, my brother is good with those volt meter thingies so I don't have to be